Objective: To assess Relative biological effectiveness (RBE) of 131I radiation Relative to 60Co gamma rays in glioblastoma spheroid cells. Materials and Methods: In this experimental study, glioblastoma spheroid cells were exposed to 131I radiation and 60Co gamma rays. Radiation induced DNA damage was evaluated by alkaline comet assay. Samples of spheroid cells were treated by radiation from 131I for four different periods of time to find the dose-response equation. Spheroid cells were also exposed by 200 cGy of 60Co gamma rays as reference radiation to induce DNA damage as endpoint. Results: Resulted RBE of 131I radiation Relative to 60Co gamma rays in 100mm giloblas-toma spheroid cells was equal to 1.16.Conclusion: The finding of this study suggests that 131I photons and electrons can be more effective than 60Co gamma rays to produce DNA damage in glioblastoma spheroid cells.

Background: This paper presents a Monte Carlo (MC) simulation study estimating Relative biological effectiveness at a 10% survival fraction (RBE10) of light ion beams by means of microdosimetric approach. Microdosimetric parameters for estimating Relative biological effectiveness (RBE) were determined through the utilisation of the Tool for Particle Simulation (TOPAS) MC simulations. These simulations incorporated a 3D silicon on insulator (SOI) Bridge microdosimeter model. Materials and Methods: The incident 176.8 MeV proton and 176.4 MeV/u helium ion beams were simulated at different depths within a water phantom. The microdosimetric aspects, such as  уF ̅ and уD ̅ at different depths along the fields were predicted from simulations. The RBE10 were derived using simulated microdosimetric spectra as inputs to the modified Microdosimetric Kinetic Model (MKM). Results: Simulated уD ̅ distributions for proton and helium ion beams in water were about 4 keV/µm and 4 to 8 keV/µm at the plateau region, respectively and around 7 to 14 keV/µm and 35 to 56 keV/µm at the Bragg peak (BP) region, respectively. In the tail region уD ̅ values were increasing from 5 keV/µm to 10 keV/µm and 7 keV/µm to 14 keV/µm at depths of 224 mm to 250 mm, respectively. Conclusion: The RBE10 for protons exhibit a range of 0.99 to 1.22, which differs from the standard practice of using a fixed RBE of 1.1 in the Treatment Planning System (TPS) for proton therapy. The simulation results in this study may be used as an outlook for radiobiological experiments in the NASA Space Radiation Laboratory (NSRL).

Background and Aim: Cancer treatment using ionizing radiation is an effective modality for the management and control of various cancers. The presence of oxygen inside the cell causes various damages to the DNA molecule. The purpose of this study is to calculate the Relative biological effectiveness (RBE) of low-energy X-rays during cancer treatment using intraoperative radiotherapy at different oxygen concentrations within the cell through a Monte Carlo (MC) simulation approach. Materials and Methods: To estimate the RBE values in this study, the secondary electron spectrum, which was emitted from 1 cm after the bare probe surface, was calculated with the Geant4-validated MC model of the INTRABEAM system. After the calculation of the secondary electron energy spectrum, the RBE values of the emitted low-energy X-rays from the INTRABEAM system at different cell oxygen concentrations were calculated by the MCDS MC code. Results: The results showed that the RBE values increase with the oxygen concentration increment in the cell. When the oxygen concentration increments from 0 to 100%, the RBESSB and RBEDSB values increase by about 1.6 and 2.3 times, respectively. Furthermore, in most of the studied oxygen concentrations, the RBEDSB values were greater than unity, which indicates the high Relative biological effectiveness of the considered low-energy X-rays compared to high-energy photons. Conclusion: Accordingly, it can be concluded that cell oxygen level is one of the influential factors for RBE assessments relevant to the emitted X-rays from the INTRABEAM system, where the cell sensitivity to the ionizing radiation decreases at low-oxygen levels.

Background: The trabecular bone changes in the tibia of C3H/HeN mice were measured 12 weeks after whole body irradiation with various doses of fast neutrons (0-2.4 Gy) or 137Cs-generated gamma-rays (0-6 Gy).Materials and Methods: Serum calcium, phosphorus, estradiol concentration and alkaline phosphatase activity were measured. Tibiae were analyzed using microcomputed tomography. Biomechanical property and osteoclast surface level were measured.Results: There was a significant relationship between the loss of bone architecture and the radiation dose, and the best-fittng dose-response curves were linear-quadratic. Mean Relative biological effectiveness (RBE) values (Ref. gamma) of 2.05 and 2.33 were estimated for fast neutron irradiation in trabecular bone volume fraction and bone mineral density, respectively. There was a substantial reduction in osteoclast surface level in tartrate-resistant acid phosphatase-stained histological sections of tibial metaphyses in irradiated mice with high dose of neutrons.Conclusion: There was a significant relationship between the loss of bone architecture and the radiation dose. The difference of osteoclastic bone resorption may represent a contributor to the low RBE in high dose of irradiation level Relative to that of low dose level.

Background: The present study aimed to provide an empirical theoretical basis for the psychological phenom-ena that occur among competing athletes. To this end, we utilized the actor and partner interdependence model (APIM) to analyze the self-and Relative effects of competitive state anxiety on perceived performance in middle and high school Taekwondo athletes. Methods: Data were analyzed for 372 middle and high school athletes (red group=186, blue group=186) who participated in the first round of the 2020 Korea Taekwondo Association National Taekwondo Competition. Analysis based on the APIM was applied to the collected data, and a path analysis was conducted to verify the self-and Relative effects of competitive state anxiety on perceived performance. Results: Cognitive (red: P<0. 01, blue: P<0. 001) and physical state anxiety (red: P<0. 01, blue: P<0. 01) exerted a significant negative self-effect on perceived performance in both groups. In contrast, state confidence (red: P<0. 001, blue: P<0. 001) exerted a significant positive self-effect on perceived performance. Furthermore, cog-nitive (red: P<0. 001, blue: P<0. 01) and physical state anxiety (red: P<0. 001, blue: P<0. 001) exerted a significant positive Relative effect on the opponent’ s perceived performance in both groups, while state confidence (red: P<0. 01, blue: P<0. 001) exerted a significant negative Relative effect on the opponent’ s perceived performance. Conclusion: Sports psychologists should focus on developing a psychological training program that provides practical psychological support as well as self regulatory and Relative strategies for improving athletic perfor-mance in competitive scenarios.

Determination of the Relative biological effectiveness (RBE) of Auger electrons is a challenging task in radiobiology. In this study, we have estimated the RBE of internal conversion (IC) and Auger electrons released during Gadolinium neutron capture reaction (GNCR) by means of biological weighting functions (BWFs) with microdosimetric approach. Regarding the different distribution of Gadolinium (Gd) Relative to the DNA as a target, the microdosimetric parameters of the Gd electrons were calculated using the Geant4 Monte Carlo toolkit and ROOT software. Assuming Gd infiltration into the cells and uniform distribution inside the Cell, the lineal energy distribution of Gd electrons in DNA was used instead of the lineal energy distribution of external radiations in the micrometer-diameter targets, which has been conventionally used in the mentioned methods. The results show that the calculated RBE values of Gd electrons using BWFs (2. 68) for the case where Gd distributed at the center of the DNA are approximately equivalent to the RBE value of the therapeutic neutrons, which were measured in the literatures with the same biological conditions. According to the results, although the changes of the RBE of Gd electrons to the different distribution of Gd Relative to the DNA are small, the amount of biological dose of the Gd electrons in the DNA is strongly dependent on the Gd distribution. In the case where Gd distributed at the center of DNA, the mean biological dose of Gd electrons in DNA during one GNCR (227. 8 kGy. Eq) is large enough for occurring double-strand breaks (DSB) of the DNA. If we have accurate information about the spatial distribution of Gd or Auger-electron emitters inside the cell, by comparing to the results obtained in this study, we can have a better estimation of the RBE of the Gd electrons or in general Auger electrons.

In radiation therapy, ions heavier than proton have more biological advantages than a proton beam. Recently, ion helium has been considered due to high linear energy transfer (LET) to the medium and a higher Relative biological effect (RBE). To design the spread-out Bragg peak (SOBP) of biological dose for radiation with any type of ion, we need exact values of RBE, which is dependent to dose, LET, and tissue specific parameter, and has spatial variations Relative to depth in the tissue. Here, we calculate the exact value of RBE in helium ion irradiating V79 cell line by applying a parametric expression for RBE variations Relative to LET, as well as using the Monte Carlo simulation code Geant4 to calculate the LET and the dose profile. The profiles of the Bragg Peak and LETs are calculated for each slice in the tumor region. To generate an appropriate biological SOBP, we compute a set of weighting factors using matrix computations, and by modulating helium ion beams, creation of optimal homogeneity at SOBP for biological doses was done.